So, I just read this thread, I would imagine the average person without a good understanding of household electricity could be confused and nervous. This should probably include anyone who doesn't truly understand the meaning and relationships of voltage, current, resistance, load, power, other terms that might well include GFI, AFI, ground etc. Maybe I can help clarify some things in this discussion even if I still have a lot to learn. I do feel understanding electricity is the safest thing someone who wants to work with electricity can do.
Most respectable electrical contractors are willing to have a look, render an opinion and/or options with reference to applicable codes. They will also provide an estimate that you can compare with other contractors, including comparable rationale.
A ground wire provides a low impedance path for an electrical fault that will trip the breaker (OCPD or over current protection device). This will result in the fault no longer being an immediate danger. Think of the hot wire in your washing machine coming in contact with the grounded chassis, causing an over current through the ground wire and tripping the breaker.
A GFI will trip whenever the current in Amps on the hot wire from the panel to the device (GFI receptacle) has a difference between the amperage on the neutral wire and the hot wire; above the rated milliamps. So, if 20 milliamps is flowing through your body to earth it would mean 20 milliamps less would be on the neutral when compared to the hot wire making the 6ma rated GFI trip and save you the shocking experience.
An ARC fault breaker will recognize a pattern of arcing in a series, or depending on the breaker rating arcing between different potentials (parallel). An arc (spark) can have an internal momentary temperature of 2000deg F. This heating will cause an ever-worsening condition that may ultimately end in insulation failure followed by ignition and fire. Consider a poor connection in a wire nut or poor contact in a receptacle, until the arcing causes failure. The arc fault breaker will trip instead.
Most household receptacles are only rated for 15 amps even if 12gauge wire and a 20-amp breaker make up the branch circuit. Of those 15 amps. only a continuous load of 80% is allowed. A branch circuit with a 20-amp breaker, 12-gauge wire, and a 20-amp rated device (identified by a unique prong shape) is restricted to 80% of 20 amps or 16 amps continuous duty.
Electrical equipment in the USA must be approved by UL or another acceptable laboratory. This approval will come with minimum safe parameters of use. A plug strip will often be rated at less than 15 amps. Any other conditions of use would be prudent to observe. Most extension type cords have a maximum rating on them when purchased.
Most electrical codes discourage the use of portable cords and do not allow for the permanent installation of extension cords. When considering electrical service, you can think, where is the weakest link? The wire, breaker, receptacle, cord, equipment etc. consider and evaluate the suitability. I believe as GRG stated if you are not exceeding the ratings of any of the equipment and it is being used in a manner that is consistent with UL or another certifying Laboratory it is fine, and I agree with GRG.
Most states do not allow an insurance company to disallow a claim based on accidental and unknowing events.
All that said, and I understand enough about household and commercial electricity and have taken my own shortcuts but only as they affect myself and no one else (I often worked hot circuits out of ease, and I paid often for that disregard.) I use cords, temp connection, and quick attachments that I am comfortable with for myself but would never dream of giving others, advice that is contrary to safe and acceptable or perform work other than in an approved manner.
The point being error on the safe side if you don't understand everything about what you are doing, your loved ones in the same house will appreciate it.
kevin
